1. Field of the Invention
The present invention relates to a probe device. More specifically, the present invention relates to a device for carrying out dopant analysis of a nano-device surface and a semiconductor; evaluation of a surface electronic state at a nano-scale of a sub-surface defect and a mezo-scopic substance etc.; and evaluation of electric conductivity.
2. Description of the Related Art
Conventionally, a measuring technique using a scanning tunnel microscope (STM) or a scanning tunnel spectroscopy (STS) is known as a technique for measuring a local electronic state in nano-scale orders of samples. In these techniques, however, it is necessary to detect a tunnel current which flows between a probe and a sample for feed back control to keep constant tip-sample separation. Thus, in the measuring techniques, only a sample having conductivity can be measured. This makes it difficult to measure an electronic state in nano-scale orders for a device structure such that a metal and an insulating material coexist. In addition, this makes it difficult to image its electronic state in a real space.
There is a measuring technique for measuring a current and a voltage while carrying out measurement with a contact-mode atomic force microscope (hereinafter, referred to as an “AFM”) by using a conductive cantilever. In this method, however, because the probe and sample always come into contact with each other, the electronic state of the sample cannot be measured. As a result, a transport phenomenon of a whole system including a junction characteristic between the probe and the sample to be measured is evaluated.
In addition, in measurement with a contact-mode AFM, an object targeted for measurement is narrowed because a substance having a weak intimacy with a substrate such as a carbon nano-tube or a DNA is pushed away by the probe during measurement.
Therefore, in a conventional measuring method using an STS or an AFM, it is difficult to measure an electronic state for a sample in which an insulation surface coexists or a substance having a weak intimacy with a substrate surface.
Further, in recent years, a device structure represented by silicon has achieved significant high performance and downsizing, and has been developed so that its size reaches a size of nano-scale orders. If the device is thus of the size of nano-scale, there is a need for a technique for locally evaluating an electrical characteristic at a portion at which a predetermined function is provided in nano-scale orders. However, a metal and an insulator coexist in such a device structure itself, thus making it difficult to measure a local electronic structure of such a sample to be measured by a conventional scanning probe technique.
On the other hand, a technique for measuring an electronic state even on a surface on which the metal and insulator coexist as described above includes a technique for measuring a charge-transfer force by means of a force curve of the contact-mode AFM. In this measuring technique, however, it is necessary to evaluate a respective one of measurement points by analyzing a force curve on one by one basis. Thus, it takes very long time to carry out measurement, and it is difficult to measure an electronic state in nano-scale orders by fixing a sample at a predetermined point or to image the measurement result. By developing measurement of this charge-transfer force in a dynamic mode, it is believed to speed up measurement of a charge-transfer force and apply to local imaging easily. However, in a non-contact mode AFM utilizing a frequency shift for detection of a weak force, control of an tip-sample distance is made by a frequency shift which depends on a force, thus making it difficult to extract and measure a force change originating from the variation of tip-sample distance.